More Scripting With Racket

:: Racket, Scripting, CrossPlatform, CodingRecipes

By: Onorio Catenacci

Using racket in a shell script to automate some repetitive commands.

Lately I’ve been looking at the Zed editor and being the sort of developer I am I wanted to see if I could get it just as nice in Windows as it is in Linux.

On Linux and Mac there’s a nice prebuilt binary available. They (the Zed folks) are working on a Windows port but for now a developer needs to built it his/herself from code. By the way I’ve got to hand it to the Zed folks—once it’s built it works very well on Windows. So to run it on Windows, I need to change to the root of the Zed source tree and then use Rust’s cargo tool to fire up the binary. Being the lazy human being that I am I wanted to automate that so that I could easily fire off Zed from anywhere. And being that I also love Racket I wanted to use my Powershell/Racket combo to automate things. Well here’s the result of that!

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; Racket.exe (Resolve-Path $PSCommandPath) $args
; Exit
#lang typed/racket/base

(require typed/racket/system)

(: ZED-PATH Path)
(define ZED-PATH (string->path "C:\\Users\\Public\\zed\\"))
(: CARGO-COMMAND-LINE String)
(define CARGO-COMMAND-LINE "cargo run --release")

(parameterize ((current-directory ZED-PATH)) (system CARGO-COMMAND-LINE))

A few comments about the script are in order I think:

  1. As you may guess I’m a big fan of Typed Racket. The two lines in front of the definitions of ZED-PATH and CARGO-COMMAND-LINE aren’t strictly needed; they’re just a way of expressing my intent.

  2. The parameterize construct (which was pointed out to me by a few of the friendly folks of the Racket community) allows me to temporarily change to another directory, run what I want there and then the directory is changed back to the original directory when the scope of the parameterize ends.

  3. In that parameterize function the function to be parameterized would normally be specified in this fashion ([current-directory ZED-PATH]). However the square brackets are special characters to Powershell and Racket allows me to use parentheses there so rather than trying to figure out how to escape the square brackets I simply using parens instead.

  4. The system function starts the command synchronously. That is, it blocks until the command exits. I wouldn’t normally want it to be synchronous but the regular async option (at least as far as I know) in Racket is process. While that seemed to work just fine as far as I could tell (I mean it looked as if everything were working as expected) it failed to actually start the binary for me.

  5. There is a command parameter to cargo that should allow me to run the binary from any directory. Again, though, for reasons I was unable to isolate I couldn’t make it work correctly with this configuration. So I simply live with having to change to the Zed source root directory while I run the command.

I just wanted to document this in case anyone else were interested!